This invention relates to a fetal monitoring device, and particularly to a fetal monitor that detects uterine contractions, determines the frequency of uterine contractions, and generates a real time graphical representation of the determined frequency.
A tocodynamometer or a uterine pressure catheter is commonly used to collect uterine activity or contraction data. These devices are pressure sensors or force transducers that monitor uterine activity by mechanically sensing the pressure caused by the uterine contraction.
In the case of a tocodynamometer, the transducer is attached to a belt that is strapped to the mother""s abdomen. During a uterine contraction, the transducer is pressed between the abdomen and the belt and a contraction is registered. In the case of an intrauterine pressure catheter, an intrauterine pressure sensor is inserted by catheter through the birth canal and into the uterus. The sensor registers the change in uterine pressure that occurs during a contraction.
The contractions are also referred to as uterine activity and the indication of such activity by the tocodynamometer or the intrauterine pressure sensor is called uterine activity data. The uterine activity data is sampled by the fetal monitor and plotted over time on a strip chart. Uterine contractions appear as humps in the waveform shown on the strip chart. Typically, a clinician visually inspects the strip chart and counts the humps to identify the frequency of uterine contractions over a given period of time, usually ten minutes.
This method of determining the frequency of uterine contractions is time consuming. The frequency of contractions is essential information in determining the progress of labor. Each time the progress of labor needs to be determined, a clinician must take the time to visually inspect the strip chart to determine the frequency of contractions. A clinician must manually record each frequency determination to compare the frequency of contractions for the current time period with previous time periods. Thus, a clinician must continually visually inspect a long strip chart to make simple assessments for determining the progress of labor.
Accordingly, the invention provides a method and apparatus for detecting uterine contractions, determining the frequency of uterine contractions, and generating a real time graphical representation of the determined frequency. Rather than using the manually recorded frequency of contractions from the strip chart, the real time graphical representation can be used to easily monitor the progress of labor. The physical representation shows the determined frequency for each time period in an easy to read format allowing for comparison between multiple time periods. A clinician can efficiently and accurately determine the progress of labor by comparing the frequency of contractions in multiple time periods.
The invention employs commonly known methods of uterine activity detection, including, but not limited to, tocodynamometers and intrauterine pressure catheters. Once the uterine activity data is gathered, a maternal/fetal monitor analyzes the data. The maternal/fetal monitor determines the occurrence and frequency of contractions. The maternal/fetal monitor trends the uterine contraction frequency data over the course of labor and generates a graphical representation of the data. The maternal/fetal monitor displays the graphical representation in the form of a time-frequency graph with a bar for every time period to indicate the number of contractions for that time period. Multiple time periods over the course of labor are displayed in real time on the maternal/fetal monitor.
The invention further includes a method of detecting and displaying uterine contraction frequency. The method includes detecting uterine contractions from uterine activity data, determining the frequency of contractions, and generating a graphical display of the frequency of contractions over real time.
The invention further includes a software program for analyzing uterine activity data. The software program determines the occurrence and frequency of contractions. The software program then generates a graphical display of the frequency of contractions over real time.
It is an advantage of the invention to eliminate the need to visually inspect a strip chart to determine the occurrence and frequency of uterine contractions.
It is another advantage of the invention to eliminate the need to manually record the determined frequency of uterine contractions in order to monitor the progress of labor.
It is still another advantage of the invention to provide an efficient and accurate method of determining and displaying the frequency of uterine contractions over real time.
Various other features and advantages of the invention are set forth in the following drawings, detailed description, and claims.